In accordance with one aspect, the invention relates to a disposable nozzle for use on a needleless injector of the type disclosed by the inventor's U.S. Pat. No. 7,357,781, issued Apr. 15, 2008. As described in the abstract, the patented injector includes a barrel for receiving an injectable liquid, a nozzle closing one end of the barrel containing an injection orifice, and a plunger and piston combination in the barrel. A valve admits gas under pressure into the barrel behind the piston. A trigger opens the valve to cause the piston to move against the plunger, and a magnet retains the piston in a rest position in the barrel until acted upon by the gas under sufficient pressure to cause the piston and plunger to move to an extended, discharge position. While the disposable nozzle is intended for use on the patented injector, it also can be used on other injectors of the same type, i.e. injectors including a barrel and a plunger for discharging a liquid through a valve and nozzle in one end of the barrel.
In the patented device, the nozzle is retained in the outlet end of the barrel by an internally threaded cap. Thus, in order to replace the nozzle, it is necessary to unscrew the cap, remove the nozzle, place a new nozzle in the barrel and replace the cap.